Merck to stop lung condition drug study early due to strong efficacy data

Jan 30 (Reuters) - Merck MRK.N plans to stop a late-stage study testing its drug to treat pulmonary arterial hypertension (PAH) ahead of time based on strong efficacy shown in previous studies, the drugmaker said on Thursday.

The therapy, branded Winrevair, is already approved for treating the rare condition which causes high blood pressure in the lungs, leading to symptoms such as shortness of breath, chest pain and dizziness.

Analysts expect Winrevair to become a multi-billion-dollar product for Merck, which has been beefing up its portfolio of cardiovascular drugs to counter a looming hit to sales of its top-selling cancer treatment Keytruda from close copies.

Merck's decision was partly based on interim data from another late-stage study, named ZENITH, in which Winrevair helped significantly reduce the risk of death in PAH patients.

"Based on the strong, positive interim efficacy data from the ZENITH trial, as well as the totality of available Winrevair data, we concluded that it would not be ethical to continue the HYPERION study," said Eliav Barr, chief medical officer at Merck.

The current study, named HYPERION, enrolled about 300 newly diagnosed patients PAH patients who were randomly chosen to receive Winrevair along with a background PAH therapy or placebo and background PAH therapy.

The trial participants would be able to continue receiving Winrevair through a separate open-label extension study, Merck said, adding that it has discussed the decision with the U.S. Food and Drug Administration.

Winrevair has brought in sales of $219 million since its launch in March. Analysts expect the drug to bring in $1.5 billion in sales this year, according to LSEG data.

The therapy is also approved in the U.K., European Union and 30 other markets.